Draw type metal punch



Dec. 12, 1961 R. J. WITTEK 3,012,458

DRAW TYPE METAL PUNCH Filed Oct. 9, 1957 E Fl 2| 2 30) 32 22 V//V/N/V/ 5 l5 6 I9 48 41a 22 46 T* 47 4L "L HTAL ' 24 RUDOLPH J. W|TTEK MLM/22 United States Patent 3,012,458 DRAW TYPE NIETAL PUNCH Rudolph I. Wittek, 14750 Keswick St., Van Nuys, Calif. Filed AOct. 9, 1957, Ser. No. 689,206 6 Claims. (Cl. 83-23) "this invention relates to a metal punch for placing holes in sheet metal panels and more particularly, relates to la metal punch of the draw type in which the removal `of the punched slug is facilitated by use of a double acting linkage for the punch.

Metal punches of the draw type have been utilized to form openings in sheet metal which forms the chassis or housing for electrical systems or devices. These openings can receive electrical Wiring or other electrical components. The prior devices commonly comprise a punch which moves into a die vto shear the slug from the sheet metal and considerable difficulty is encountered in removing the slug from the die even though the slug is somewhat bent during the punching operation. Also, no provision has been made for quickly and easily changing the shape and the size of the die and of the punch. Some prior devices in the form of a punch press do not permit holes to be punched at considerable distances from the edge of the sheet metal.

The present invention employs a double-acting lever arrangement for positively moving the punch into and out of the die and a shoulder is provided on the arm connected with the punch to enga-ge and remove the slug 'from the die as the punch is moved out of the die after the punching operation. The metal punch is mounted on a base plate which can be secured to the edge of a Work table so that holes can be punched in any location in a large metal sheet. The die is secured for quick removal so that the device can be quickly modified to punch various sizes and shapes of holes.

It is therefore an object of the invention to provide a metal punch which the punched slug can be easily removed from the die.

Another object of the invention is to provide power means for positively moving the punch of a metal die in opposite directions to permit removal of the punched slug by the power means.

A further object of the invention is the provision of an easily replaceable punch and die for a metal punch to facilitate the punching of various sizes and shapes of openings.

These and other objects of the invention not specifically set forth above will become readily apparent from the accompanying description and drawings in which:

FIGURE l is a perspective view of the metal punch of the invention in readiness for punching an opening;

FIGURE 2 is a vertical section along line 2--2 of FIG- URE l showing the position of the punch before and after the punching operation;

FIGURE 3 is a vertical section similar to FIGURE 2 showing the outward position of the punch and the manner in which the slug is removed by the ejection shoulder;

FIGURE 4 is a section along line 4-4 of FIGURE 3;

FIGURE 5 is a horizontal section along line 5-5 of FIGURE 2 illustrating the linkage mechanism for moving the punch.

Referring to FIGURE l, the metal punch 10 includes a base or mounting plate 11 having openings 12 at the corners for receiving bolts 13 which serve to rigidly attach the plate to a bench support 14. A punch body 15 is secured to plate 11 by four screws 16 having heads located in openings in the plate. One end 17 of body 15 projects beyond the edge of plate 11 and support 14 and contains a circular opening or die socket 18 which snugly receives a tubular shaped die 22. The die is retained within the opening 18 by set secrew 20 which is tightened ice against a depressed surface 21 of the die to prevent rotational and axial movement of the die. Also, the cutting end 22 of the die projects beyond the end 17 of body 15 so that body 15 does not interfere with the punching action.

An opening 23 in body 15 is coaxial with opening 18 and contains a bushing 24 for slidably supporting a punch rod 25. One end of rod 25 carries an enlarged rectangular member 26 which is pivotally connected with one end of links 27 and 28 by a pin 29 passing through the links and member 26. The body 15 has an extension 30 projecting rearwardly above the links 27 and 28 and the extension has an opening 31 containing a bushing 32. An opening 33 is located in plate 11 directly opposite opening 31 and also contains a bushing 34.

Located between plate 11 and extension 30 is a circular crank member 35 which has offset end pinions 36 and 37 received by the bushings 32 and 34, respectively. A lever arm 38 extends through opening 39 in member 35 and has a attened end 40 which is pivotally connected -With the other ends of links 27 and 28 by a pin 41. The

crank member 3-5 is provided with a at surface 42 of greater length than pin 41, which results in a slot 43 in member 35 which can receive the links 27 and 28 as the member 35 is rotated in a clockwise direction by lever arm 38. The arm 38 passes through the flat surface 42 and has two shoulders 44 and 45 located at the flattened end 46 and within slot 43.

As illustrated in FIGURES 2 and 3, movement of arm V38 in a counter-clockwise direction will cause links 27 and 28 to extend rod 25 out of die 19 until member 26 abuts body 15.V Also, clockwise movement of arm 38 will cause links 27 and 28 to Withdraw rod 25 until the ends of the links 'enter slot 43 and abut shoulders 44 and 45, respectively. The axis of pinions 36 and 37 is offset from the axis of punch rod or shaft 25 so -that in the extended position of rod 25, -the 1inks'27 and 28 are in line with the rod 25 and the links assume only a small angle to the rod axis in the withdrawn position of the rod 25. A large mechanical advantage results from pivoting long lever arm 38 at pinions 36 and 37 and connecting the short flat end of the arm with the links 27 and 28 and because of the position of the links, the full force applied to the links is effective on the punch rod 25.

i End 46 of rod 25, opposite member 26, is threaded and has an ejection shoulder 47 which is located beyond the end 22 of die 19 when the rod is fully extended. A punch member 48 has a central threaded opening so that the member can be secured to end 46 for movement by the punch rod 25. The punch 48 is of slightly smaller diameter than die 19 to be received thereby and has two points 49 and 50 which serve to initially pierce the sheet metal. Portions 51 and 52 recede from the points 49 and 50 and provide shear edges which progressively cooperate with die 19 to cut a round slug from the sheet metal as the punch is drawn into the die by the rod 25 Prior to assembling the metal punch for a punching operation, small centering holes 53 are placed in the sheet metal section 54 at the locations where openings are to be punched. Since the die 19 extends beyond the edge of the support 14, the section 54 can be moved vertically to locate an opening at any desired location from its edges, without interference from fthe metal punch. The holes 53 will receive threaded end 46 but will not receive rod 25 so that when the end 46 is inserted into a hole 53, the sheet metal around the hole will abut ejection shoulder 47. Thereafter, the punch 48 is threaded onto end 46 until the points 49 and 50 engage the surface of the sheet metal. The initial clockwise movement of lever arm 38 by knob 55 will move the linkage to locate the section 54 against end 22 of die 19 as illustrated by the full line position of FIGURE 2 and further movement will cause points 49, 56 and edges 51, 52 of the punch to cut a circular slug 56 from the section 54 as illustrated by the dotted line position of FIGURE 2. As previously described, the clockwise movement is limited by engagement of links 27 and 28 with shoulders 44 and 4S and at the limit position, the body of punch 48 extends from the die to support section 54.

During punching of the slug 56, the slug will bend at its edges to substantially conform to the contour of the cutting edges of the punch while the center of the slug will remain adjacent the ejection shoulder 47. (See FIGURES 3 and 4.) After the punching operation, reverse movement of the lever arm 38 in the counterclockwise direction will cause the ejection shoulder 47 to forcibly move slug 56 out of die 19 (as illustrated in .FIGURE 3) at the same time as the punch 48 is removed from the die. Thereafter, the punch 48 and the slug 56 can be easily removed from end 46 and the device is :ready for another punching operation. The positive removal of the slug is possible because of the double action of the lever arm and linkage connected to the Ypunch 48.

The lever arm 38 is of proper length to develop the required punching force without excessive exertion by the operator. If it is desired to punch after than a circular hole in the sheet metal, the die 19 can be easily removed and replaced with a die having an'opening of the desired shape and a punch corresponding in shape to the new die can be attached to end 46. It is apparent that the present invention also provides a method of punching in which a small opening in the metal sheet first receives the end of the punch rod and the reverse movement of the punch rod removes the slug. While ejection shoulder 47 is provided for positive removal of the slug, other means attached to rod 25 can be used for this purpose, in which case, the end 46 could be of the same diameter as the rod. Various other modifications are contemplated by those skilled in `the art without departing from the spirit and scope of the invention as hereinafter dened by the appended claims.

What is claimed is:

1. A method of forming an opening in a metal sheet by drawing a punch on the Vend of a shaft into a hollow die to remove a slug comprising the steps of placing a small opening in the metal sheet, placing the sheet against a shoulder of the shaft for the punch, attaching the punch onto the end of the shaft to hold the metal sheet against the shoulder, moving the sheet against the die, forcing the punch through the sheet by force on the shaft, and removing the slug formed by the punch from the die by an opposite force on the shaft transmitter to the slug by the shoulder.

2. A metal punch for forming an opening in a sheet of material, comprising a hollow die, shaft means having one end thereof reduced in diameter and threaded, said shaft means extending through said die and having said onerend extending through an opening in said sheet material, an ejection shoulder at the inner end of said threaded portion of said one end of said shaft means and of Ylarger diameter than said opening, punch means threaded onto said one end of said shaft means and into engagement with said sheet to hold said sheet against said ejection shoulder and substantially perpendicular to the axis of said hollow die, and double acting power means connected to the other end of said shaft means for moving said punch means throughsaid sheet material into said hollow die to form an opening in said sheet by removal of a slug of sheet material and for thereafter forcibly removing said slug from said die by said ejection shoulder.

3. A metal punch as defined in claim 2 wherein said double acting power means comprises linkage means for positioning said ejection shoulder in line with the edge of said hollow die prior to movement of said punch through said sheet material so that said linkage means commences the punching action from a given predetermined position for all thicknesses of sheet material.

4. A metal punch device for forming an opening in a metalV sheet comprising a hollow die, means for holding said hollow die, a single shaft member extending through said die, punchmeans connected to one end of said shaft member, said metal sheet being initially positioned between said die and said punch means, double acting power -means connected to the other end of said shaft member, actuation of said power means in one direction causing movement of said punch means into said die to remove a slug from said metal sheet and form an opening therein, and means carried by said shaft member for forcibly removing said slug from said'die upon actuation of said power means in the other direction, said removing means comprising an ejection shoulder on said shaft member of larger diameter than said one end of said shaft member, said metal sheet initially containing a small opening receiving said one end and smaller than said shoulder so that said shoulder directly engages said slug around said small opening to forcibly remove said slug without binding in said hollow die, said removing means being continually located in engagement with the portion of said metal sheet forming said slug during formation of said opening and removal of said slug from said die.y

5. A metal punch as defined in claim 4 wherein said holding means comprises a body member having a socket for snugly receiving said die, and releasable means for securing said die in said socket to permit replacement of the die with `a die of different size corresponding to a dif- 'ferent size of punch means attached to said shaft member. 6. A-metal punch as defined in claim 4 wherein said holding means comprises a body member having a socket for supporting said die, an opening throughv said body member to receive said shaft member for slidable support by said body member, said double acting power means comprising linkage means pivotally connected to said other end of said shaft means and rotatable lever means pivotally connected with said linkage means.

References Cited in the le of this patent UNITED STATES PATENTS V1,540,860 Pobanz June 9, 1925 1,884,398 Uxley Oct. 25, 1932 2,276,259 Temple c Mar. l0, 1942 2,633,197 Nischan Mar. 31, 1953 2,643,721 Arbuckle June 30, 1953 2,787,324 Hartmeister Apr. 2, 1957 

